Swelling and softening behaviour of La Biche shale

Wong, R.C.K.

doi:10.1139/t97-087

Cited by 95 publications

(38 citation statements)

References 7 publications

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“…The disjoining pressure is thus a microscopic concept which must be analyzed at the pore scale. The macroscopic swelling pressure which can be measured in natural materials [see, e.g., Madsen and Vonmoos, 1985;Huang et al, 1986;Wong, 1998] is associated with the wellknown swelling properties of certain clays (e.g., smectite). This pressure is currently described as the external stress that has to be applied to a clay-rock sample in order to maintain its mechanical equilibrium (prevent swelling).…”

Section: Introductionmentioning

confidence: 99%

What is the significance of pore pressure in a saturated shale layer?

Gonçalvès

Rousseau-Gueutin

Marsily

et al. 2010

Water Resources Research

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International audienceElectrostatic interactions, associated with negatively charged surfaces of clay minerals, produce a so-called "disjoining pressure" when diffuse layers overlap, i.e., at low porosity. Disjoining pressure is the pressure difference between the water in the clay pore space and that in a bulk solution at the same depth. Another widely used concept in clay-rocks is the "swelling pressure." It corresponds in fact to the macroscopic average of the disjoining pressure. This study proposes to determine the value of the swelling pressure of a natural material by a simple volume-averaging approach of the disjoining pressure, calculated for each clay mineral present in the material. The swelling pressure, which is dependent on the salinity of the pore fluid, is introduced into a hydrochemomechanical coupling, yielding a more general pressure diffusion equation. The results are compared to swelling pressure measurements for natural shale samples. The implications of this swelling pressure for water pressure measurements in natural formations are also discussed

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Section: Introductionmentioning

confidence: 99%

What is the significance of pore pressure in a saturated shale layer?

Gonçalvès

Rousseau-Gueutin

Marsily

et al. 2010

Water Resources Research

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“…He also investigated the effect of swelling under different salt concentrations of the water added in swelling tests. (b) swollen specimens at a confining stress of 50 kPa (after Wong, 1998) stress, a profound degradation in strength and stiffness is observed in the subsequent triaxial test (Fig. 7(b)).…”

Section: Drying-wetting Cyclesmentioning

confidence: 97%

“…The behaviour of La Biche shale (Wong, 1998) The particular triaxial tests reproduced in Fig. 7(b) were selected for the comparison exercise.…”

Section: Modelling Some Reported Experimentsmentioning

confidence: 99%

A constitutive model for soft clayey rocks that includes weathering effects

Pinyol¹,

Vaunat²,

Alonso³

2007

Géotechnique

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Microstructural and mineralogical observations of claystones reveal the presence of clay aggregates bonded by a skeleton of inert minerals such as calcium carbonate. The behaviour of these natural materials evolves from a rock-like behaviour, when undisturbed, to clay-like soil when weathered or when subjected to straining. A model has been developed to simulate the constitutive behaviour of these transitional materials. Following the proposal made by Vaunat & Gens, the material is conceived as a composite medium made of a clay matrix and a quasibrittle bonding microstructure. The basic model has been modified and extended to reproduce the expansive behaviour of the clay matrix, a fundamental aspect to simulate weathering effects, induced largely by drying-wetting cycles. The clay matrix reacts to stress and suction changes, whereas the bond component is not affected by suction changes. An elasto-plastic double-structure model for expansive clay soils describes the clay matrix. The bonding structure follows a damage model. The interaction between the two constitutive models derives from strain compatibility conditions and energy considerations. The model performance is first illustrated by means of a sensitive analysis that explores the effect of initial bond strength, bond damage rate, bonding concentration, and wetting-drying cycles. Simple stress paths (uniaxial deformation; triaxial compression) are used to highlight the features of the formulation and the role of significant parameters. Some published tests are also reproduced with the model. They have been selected to show some relevant features of evolving soft clay rocks: stiffness and strength degradation during loading and enhanced rebound during unloading, and the effect of drying-wetting cycles on subsequent stiffness and strength degradation.

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“…Al-Mhaidib and Al-Shamrani [10] reported that the shear strength of the expansive shale and bentonite, obtained from triaxial testing, decreased by 70% to 90% because of a full swelling. Wong [11] investigated the effect of both swelling and confining stress on the shear strength of an expansive shale, and found that the shear strength of the tested shale decreased with increasing swelling. Zhang et al [12] discussed the impact of wet-dry cycles with loading on the expansive soil strength but did not give specific values for shear strength parameters.…”

Section: Introductionmentioning

confidence: 99%

Surficial Failure of Expansive Soil Cutting Slope and Its Flexible Support Treatment Technology

Xiao

Yang

Zhang

et al. 2018

Advances in Civil Engineering

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e surficial failure of most expansive soil cutting slopes, subjected to the repeated wet-dry cycles, often occurs during or after rainfall following a long drought. e reason for this, however, is still unclear. erefore, the laboratory tests were conducted to gain the saturated drained shear strength of the natural Nanning expansive soil considering the combined effects of swelling with loading and wet-dry cycles. e findings indicate that the envelope of shear strength, which significantly drops close or equal to zero, can be well fitted by the generalized power function. At the same time, the effect of shear strength parameters on the stability of the expansive soil cutting slope was investigated. e reasons for the shear strength attenuation of the natural expansive soil and the surficial failure of the expansive soil cutting slopes were analyzed. It is evident that the effective cohesion being small is a vital factor influencing the occurrence of surficial failure of an expansion soil slope. Moreover, an effective flexible support treatment measure was provided.

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Swelling and softening behaviour of La Biche shale

Cited by 95 publications

References 7 publications

What is the significance of pore pressure in a saturated shale layer?

What is the significance of pore pressure in a saturated shale layer?

A constitutive model for soft clayey rocks that includes weathering effects

Surficial Failure of Expansive Soil Cutting Slope and Its Flexible Support Treatment Technology

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